THIS SYSTEM PREPARES THE BODY FOR FIGHT OR FLIGHT. IT INCREASES
PHYSIOLOGICAL AROUSAL AND PREPARES THE BODY TO RESPOND TO
THREATENING SITUATIONS QUICKLY. THE ACTIVATION OF THIS SYSTEM IS A
VITAL PART OF THE BODY'S RESPONSE TO STRESSFUL STIMULI.
THE PARASYMPATHETIC NERVOUS SYSTEM
THIS IS THE SYSTEM THE BODY IS IN MOST OF THE
TIME. IT IS CALLED REST AND DIGEST. THE
SYMPATHETIC BRANCH SLOWS THE BODY DOWN
AND IS USED IN NORMAL STATE - WHEN THE BODY
IS NOT STRESSED.
THE HYPOTHALAMUS
THE HYPOTHALAMUS IS A GLAND IN THE BRAIN. IT
IS RESPONSIBLE FOR MANY PHYSIOLOGICAL
FACTORS SUCH AS HUNGER, THIRST AND STRESS.
THIS SPECIFIC GLAND ACTIVATES THE
SYMPATHETIC BRANCH OF THE AUTONOMIC
NERVOUS SYSTEM AS WELL AS THE PITUITARY
GLAND.
THE HORMONES
ADRENALINE INCREASES: ENERGY TO MUSCLES,
HEART RATE, BREATHING RATE, BLOOD PRESSURE,
SWEATING. SLOWS DOWN DIGESTION TO SAVE
ENERGY FOR FIGHT OR FLIGHT.
NORADRENALINE INCREASES: BREATHING
RATE, BLOOD PRESSURE, BLOOD FLOW TO
MUSCLES. SLOWS DIGESTION AND
RELEASES SUGAR FROM LIVER.
CORTISOL IS SECRETED WHEN DEALING
WITH LONG TERM STRESS. IT HELPS
MAINTAIN A STEADY SUPPLY OF BLOOD
SUGAR FOR INCREASED ENERGY.
SHORT TERM STRESS: SYMPATHETICOMEDULLARY PATHWAY
HIGHER BRAIN CENTRES EVALUATE THE SITUATION AS STRESSFUL AND
INSTRUCT THE HYPOTHALAMUS TO TRIGGER THE SYMPATHETIC BRANCH OF THE
AUTONOMIC NERVOUS SYSTEM. THIS STIMULATES THE ADRENAL MEDULLA, VIA
NERVES, RESULTING IN THE RELEASE OF ADRENALINE AND NORADRENALINE
INTO THE BLOOD STREAM. THIS INCREASES THE HEART RATE AND BLOOD
PRESSURE.
LONG TERM: PITUITARY-ADRENAL SYSTEM
HIGHER BRAIN CENTRES EVALUATE THE SITUATION AS STRESSFUL
AND INSTRUCTS THE HYPOTHALAMUS TO STIMULATE THE PITUITARY
GLAND. THE PITUITARY GLAND RELEASES ADRENOCORTICOTROPHIC
HORMONE (ACTH). THIS TRAVELS TO THE ADRENAL CORTEX TO
STIMULATE THE RELEASE OF CORTICOSTEROIDS - SPECIFICALLY
CORTISOL - INTO THE BLOOD STREAM. THIS SUPPRESSES THE
IMMUNE SYSTEM AND MOBILISES FAT STORES TO BE USED AS
ENERGY.
THE IMMUNE SYSTEM
NATURAL IMMUNITY
THIS IS A PRIMITIVE SYSTEM
COMPRISING OF WHITE BLOOD
CELLS (NATURAL KILLER
CELLS) THAT
NON-SPECIFICALLY DESTROY
INVADING PATHOGENS. THIS
SYSTEM IS ACTIVATED WITHIN
A FEW MINUTES OR HOURS.
SPECIFIC IMMUNITY
THIS IS A SOPHISTICATED SYSTEM.
LYMPHOCYTE CELLS RECOGNISE INVADING
PATHOGENS AND PRODUCE SPECIFIC
ANTIBODIES TO DESTROY THE PATHOGEN. THIS
EVOLVES OVER A FEW DAYS OR WEEKS AS IT
TAKES TIME FOR THE BODY TO RECOGNISE
PATHOGENS AND CREATE ANTIBODIES.
CELLULAR IMMUNITY
A VARIETY OF T LYMPHOCYTES LAUNCH AN
INTERCELLULAR PATHOGENS. (THEY ATTACK
FOREIGN CELLS HARBOURING VIRUSES)
HUMORAL IMMUNITY
B LYMPHOCYTES RELEASE ANTIBODIES TO
ATTACK AND DESTROY EXTRACELLULAR
PATHOGENS. B LYMPHOCYTES ARE
INVOLVED IN INFECTION CONTROL.